Die casting apparatus



Mam}! 1965 A. A. JOHNSON am CASTING APPARATUS INVENTOR.

3 Sheets-Sheet 1 Filed July 12, 1963 March 9, 1965 A. A.. JOHNSON3,172,174

DIE CASTING APPARATUS Filed July 12, 1963 3 Sheets-Sheet 2 IIIIIIA 7; 4

U19 INVENTOR.

March 9 1965 A. A. JOHNSON DIE CASTING APPARATUS 3 Sheets-Sheet 3 FiledJuly 12, 1963 EiEu-E-EIY United States Patent 6 3,172,174 DIE ASTHNGAPPARATUS Arthur A. lehnson, Bridgeport, Conn, assignor to AutomaticCasting Corporation, Bridgeport, fiomn, a corporationof IonnecticutFiled Iluly 12,1963, Ser. No. 2%,528 7 Claims. (Cl. 2270) The presentinvention relates to novel automatic diecasting apparatus and moreparticularly to improvements whereby the problems arising from thefreezing of molten metalin the nozzle section of the gooseneck and/orthe drippage-of molten-metalonto the open die faces are substantiallycompletely avoided.

Conventional automatic die-casing machines are in widespread use butsuch machines encounter a very high shutdown time due to the fact thatthe molten metal solidifies in the nozzle section of the moltenmetalsupplying gooseneck. When this occurs, due to the contact of thenozzle section with the dies being cooled, the machine must be stoppedand heat-must be applied to the nozzle-to melt the solidified metal andopen the passage within the nozzle. Such down time may equal about 30%or more of the total operating time of the machine.

Another important problem encounteredwith conventional automaticdie-casting machines is the drippage of molten metal from the cast sprueor sprue opening onto the open die faces. The tip of the cast spruesolidifies far less quickly than the remainder of the casting in thatitis in contact with the hot injection nozzle. Thus many times the tip ofthe sprue may not be solidified when the diesare opened and thisgenerally causes drops of molten metal to fall .from the tip of thesprue and against one of the open faces of one of the dies Where itquickly cools and solidifies. Thus when the die faces come together inthe next. casting operation, the deposited solidified drops of metalprevent complete closingof the dies and result infaulty castings.sometimes are provided with wire brushes whichsweep the die faces cleanafter each casting operation but suchbrushes are not always effectiveand also add a timeconsuming step to each casting operation.

It is an object of, this invention to provide. a novel apparatuswhereby. the problem of the freezingor solidification of the moltenmetal in the nozzle and'upper gooseneck section is-substantiallycompletely avoided and the shut-down time due, to such, cause iseliminated.

It-is another object-of this invention to provide .anovel' apparatuswhereby dripping of molten metal from thesprue tip or sprue hole ontothe die faces as the dies open is avoided.

These and other objects and advantageswillbe apparcut to those skilledinthe art in the light of. the present disclosure which:

FIGURE 1 is a side'viewofa part of an automatic die-casting machineaccording to one embodiment of'the invention showing the dies in openposition.

FIG. 2 is a top view of the pinion and rack arrangement controllingrotation of the injection plunger and taken along the lines 22 of FIG.1.

FIG. 3 is a top view of the injection cylinder and the fill-port-closingextension of the injection plunger taken along the 1ines-33 of FIG. 1but showing the plunger extension in passage-closing position.

FIG. 4 is a fragmentary sectional view showing the shot plunger. in itslowermost position.

FIG. 5 is a sectional view of part of an automatic diecasting machineaccording to the invention showing the parts of the machine in thepositions'which they occupy during the solidification of the casting.

Die-casting machines including the accompanying drawings in.

ice

FIG. 5a is a vertical section of the. shotcylinder and plunger showing amodification of the plunger shown in. FIG. 1.

FIG. 6 is a diagrammatic view of an .autornaticdiecasting machinemechanism according ,tothe embodiment, of the present inventionillustrated in FIG; 1.

FIG. 7 is a side view ofa part of an automatic diecasting machineaccording to another embodiment'of this invention with the'parts intheir positions; while the die; parts are separated. I i I FIG. 8 isadiagrammatic view-of "an automatic diecasting machine mechanismaccording'to theembodiment; of the invention-illustrated by FIG.'7.

FIG. 9-is a fragmentaryfviewoftheshot'cylinder plunger and sleeve valveshown in FIG. -7."

Referring to the drawings, FIG. lillustrates thed'reg castingmachineready for thestart of a: new casting; cycle. The machinecomprises afurnace 1" havinga heating chamber 2 and -an opening 3*providingaccessfor a gas flame orother heat-supplying means; Into the:heating. chamber is mounted a pot-4for maintainingjhe casting metal 5in-h'ot molten-condition. Thorighriot essential to the operation ofthe'present-invention, the pot is preferably separated-into tworeceptacles;qA{ and B, by meansof a partition 6, as illustrated,andthe'leyelj of the moltenmetal in the injection pot A- is maintainedconstant by means described below.

Within the. supply pot-'Ais-mounted a metal injection mechanism14:having--a shot'cylinder15; a gooseneck" section 16:.provided attheupper endWithanozzle'17 communicating. with a sprue-opening'lfi of astafi nary die 19 which is mounted infixedpo sition on the frame 2%) ofthe machine. A plunger rod 21 has an'inje tlQ i plunger 22 which .is.slidablymou-nted within thecylinder-f 15, and a piston 24 which isreciprocated within'a cyl= inder 23 by means of oil pressure alternatelyexerted and exhausted'throughlines 25-,and 25a which are asso ciatedwith. a, reversing.valve 26- controlled by a timer 26aand-a switch26b,as shown in FIG. 6 of theadrawings.

The movable die system inthe form shown-co mprisies a movabledie.'block.12 which' is slidably attachedto. the frame 20, of theymachine by. means of--guide-rods -31 and bearings 32. The: movable.-die-2 9 is attached'to; the die block and is associatedrwithejection-meansfoe removing the solidified casting from acore 33 towhichit may remain attached'supon separation Of the dies.

The; ejection means comprises ejector rods .34 afii xed to the rear ofthe ejector plate-35iiand knockout pins36 affixed to the front-Tot: the.ejector; plateand passing through openings-in the. die, 29. In :theclosed-position; shownby FIG. 5; the-ejectionplateti'si andthedie29 areforcedapart-,by; means ofsprings..37 mounted on the knockout pins Asthemovahlediesection is brought to the open position, the ejector rods 34make contact with an ejector block; 38, a sectionof which isjshown inFIG. 1, depressingthe.springs-7 and forcing the tips; of the knockout PiP s t emm-su acetq itheidream. to eject-the-casting fromthecore 33;

The movable; die blockimactivatedmeans;.of-- od; 39 which is attachedto. the die carrier 12 as how ,1 in FIG. 1, andwhich has a, piston 40attached'to the; opposite end as. shown in, FIG 6, said-;pi storr-;being-j; mounted Withinacylinder- 41. and;being;adap te,d for 15915ward and backward motion. inoresponse to oil pressure exerted throughlines 42.' The motion otthe piston, 4 t is controlled by a reversingvalve ,44,. Wl1ficl1 isafsso ated Witha timer and a switch.46 which", inthe for shown, is engaged by aswitch operating armflfiq adaptedf to beengaged by a cast piece ejected from the di'eljl)- falling on a chute46b to 'cause the die '29;to close o r the die. 19. and start anew.cycle ofoperations; If desired, the switch 46 -or-- alike switch may beoperated manually. The timer 45 keeps the dies closed for apredetermined time interval at the end of which the dies automaticallyseparate.

- In conventional die-casting methods and apparatus, when the dies areclosed the switch 2612 causes the reversing valve 26 to apply fluidpressure to the top of the piston 24 causing the plunger 22 to descendin the shot cylinder and forcing the molten metal up through thegooseneck 16 and the nozzle 17, into the sprue hole and the cavityformed between the dies 19 and 29 to fill the cavity. As soon assufficient time passes to allow the metal in the dies to partiallysolidify, the timer 26a causes the valve 26 to apply fluid pressure tothe lower side of the piston 24 and move the plunger rod 21 to the upperlimit of its movement. During this operation the molten metal in thenozzle and adjacent part of the gooseneck is withdrawn by suction, butas soon as the lower end of the piston passes the fill-port 14a themolten metal surges into the shot cylinder 15 and causes the gooseneckand nozzle to be filled. The dies being still closed and the metal inthe cavity and sprue continuing to solidify, frequently the "moltenmetal returned to the nozzle also solidifies with the result that tosuccessfully complete a subsequent operation the nozzle must be freed ofthe frozen metal which requires shutting down the machine and loss oftime. This happens more frequently when the stationary die 19 has becometoo cold. On the other hand, if the stationary die and nozzle become toohot, the metal in the sprue does not solidify and, as a result, when thedies are opened molten metal may drip off the end of the sprue or out ofthe sprue hole onto the face of the die 19 and/or onto the face of themovable die 29. The metal so deposited on the die members freezes andthus prevents the dies from reclosing completely, with the result thatthe next articles to be cast will be malformed and/or have excessiveflash, the molten metal running in the space caused by the separation ofthe dies by the metal freezing on the face thereof.

According to the apparatus herein disclosed, these difficulties areavoided by providing improved means for preventing the molten metal fromfilling the gooseneck or reaching the nozzle until the dies have beenseparated and yet permitting the plunger to be quickly returned its fullstroke to the upper limit of its movement.

' To accomplish this, the fill-port 14a is controlled independently ofthe vertical movements of the plunger and is controlled by the openingmovement of the dies. For this purpose, in the form of the inventionshown in FIGS. 1 to 6, the plunger 22 is made to perform a dualfunction-(Ute act in pumping, and (2) to act as a valve closing thefill-port 14a.

In the specific form of the invention shown in FIGS. 1 to 6, the valvingfunction of the plunger 22 is performed by an arcuate depending flange22a on the bottom end of the plunger andthe plunger is rotated betweenpositions 'in which the flange-valve 22a closes or opens the fill-portIn FIG. 3, the flange 22a is shown as closing the fillport 14a in fulllines, and in dotted lines in the position which it occupies when thefill-port 14a is open.

In the form of the invention shown in FIGS. 1 to 6, the plunger 22 isrotated by means of a pinion 28 mounted on the plunger rod 21 andadapted to be engaged by a rack 27 mounted on a rod 11 adjustablysecured by nuts 13 on the threaded end 11a of the rod to the die block12 so as to reciprocate therewith so that as the die block 12 movesbetween die-opening and closing positions, the plunger 22 will berotated.

As shown in FIG. 1, the dies are separated and the plunger 22 is in theposition exposing the fill-port 14a. As the movable die 29 approachesthe fixed die 19, the rack 27 will cause the pinion 28, rod 21 andplunger 22 to rotate from the dotted-line position shown in FIG. 3 in aclockwise direction to the full-line position shown in which thefill-port 14a is closed and at which time the dies are also closed.

When the dies close, the arm 12a on the die block 12 engages the switch261) and causes, in the manner previously explained, the plunger 22 todescend and force the molten metal trapped in the shot cylinder 15 upthrough the gooseneck and nozzle into the die cavity. After a perioddetermined by the timer 26a, the plunger 22 is raised to the limit ofits movement sucking back the metal from the nozzle and upper portion ofthe gooseneck. Since, during this return movement of the plunger 22 toits upper limit the flange 22a is in position to keep the fill-port 14aclosed, the level of the molten metal in the gooseneck is maintained tothat shown in FIG. 4, and therefore does not lie in the nozzle or theadjacent part of the gooseneck, thereby isolating the molten metal fromthe sprue which may therefore solidify without being prevented fromdoing so by molten metal and avoiding the freezing of the molten metalin the nozzle.

The dies are maintained closed by operation of the timer 45 for apredetermined time interval after which, by operation of the piston 40,the movable die 29 is moved away from the fixed die 19. In moving awayfrom the fixed die 19, the movable die block 12 moves the rod 11 to theleft as shown in FIG. 1 and this causes the plunger 22 to rotate fromthe full-line position shown in FIG. 3 to the dotted-line position.

The arcuate length of the flange 22a is such that the fill-port 14aopens sometime after the dies are parted and before they are in the fullopen position, allowing the level of the molten metal in the gooseneckto equalize hydrostatically with the level of the metal in the pot A andexclude the air from the gooseneck. The nozzle 17 is so situated withregard to the level of the molten metal in the pot A that it will notoverflow through the nozzle, there being no vacuum in the gooseneck andnozzle when the fill-port 14a opens to cause the metal to be sucked upinto the nozzle and against the sprue as in conventional methods andapparatus.

The rack 27 is horizontally and adjustably attached to the rod 11 withina slot 27a and is locked in the desired position by means of bolts 27b.The location of the valve element 22a relative to the fill-port 14a maybe adjusted by changing the position of the rack 27 or by adjusting theposition of the rod 11 on the die block 12 by means of the nuts 13. Inthis way the opening and closing of the fill-port may be closelycontrolled and the machine may be set at the point at which the bestresults are obtained.

Thus, while the segmented circumferential valve ele* ment 22a preferablyhas a surface area of about as illustrated by FIG. 3 so that thefill-port is not uncovered immediately upon separation of the dies andwhile the valve element is generally positioned so that it completelyuncovers the fill-port when the dies are in the open position, as shownby broken lines in FIG. 3, it may be found preferable to adjust theposition of the rack 27 and/or the rod 11 so that the fill-port 14abegins to be uncovered as soon as rotation is imparted to the piston 22or so that the fill-port 14a is never completely uncovered by the valveelement, whichever effect may be found most preferable.

It is an advantageous feature of this invention that the fill-port isclosed and opened by the movement of the movable die holder mechanicallythereby obviating the need for auxiliary means for accomplishing theresult.

The level of the molten metal in the gooseneck section is preferablykept high and as close to the opening in the nozzle as practical inorder to reduce the amount of air present in the gooseneck section andnozzle since excess amounts of air forced into the die cavity during thecasting cycle result in defective castings containing air pockets andsurface blemishes. This is preferably accomplished as shown in FIG. 1 bymeans of an automatic ladling device 60 which is adjustably mounted onthe rod 11 and which serves to transfer from the pot B to the pot A anamount of molten metal equal to the amount of molten metal used in eachcasting operation.

The ladle 60 is pivotally mounted on a shaft 61 and which is slidablysecured by a pin 62 in a slotted member 63 which is adjustably mountedon the arm 11. Thus, as each new casting is formed and the dies areopened, the horizontal movement of the rod 11 causes the ladle 60, whichhad been submerged in the molten metal of the pot B, to rise to theposition shown in FIG. 1 whereby molten metal spills from the ladle intothe pot A. Any excess metal spills back into the pot B over thepartition 6 so that the level of molten metal in the pot A is maintainedconstant for the start of each casting cycle.

Since the opening of the fill-port 14a prior to the start of eachcasting cycle causes the molten metal to flow into the gooseneck untilit reaches a hydrostatic level equal to the level of molten metal in thepot A, it is preferred that the height of the partition 6 be just belowthe height of the nozzle opening, as shown by FIG. 1, so that as littleair as possible must be injected into the casting.

While the form of the invention illustrated by FIGS. 1 to 6 of thedrawings relates to the embodiment in which the opening and closing ofthe fill-port 14a is controlled by a rotatable plunger provided with aflange-valve and rotation of the plunger is controlled by its mechanicalassociation with the movable die block, it should be understood that thepresent invention is not limited to such embodiment but includes on abroader scope any automatic die-casting machine in which the plunger isallowed to return quickly to the full extent of its upward motion whilethe fill-port is maintained closed by means of a valve until after thecasting has solidified and the dies have separated,

Likewise it is not necessary that the valve for closing the fill-port bea flange depending from the injection plunger, or that the injectionplunger be rotatable. Thus, in the embodiment of the inventionillustrated by FIG. 7 of the drawing, the die-casting apparatus may besimilar to conventional apparatus of this type except that a verticallyslidable sleeve 54) is provided which is inserted between thecircumference of the plunger 22 and the interior wall of the injectioncylinder 15. The lower section of the sleeve 50 extends close to thebottom of the injection cylinder and closes the fill-port 14a to sealthe same when the sleeve is in the lowered position, as illustrated inFIG. 9.

The sleeve 50 has a hole 50a so placed that when the sleeve is in itsuppermost position the fill-port 14a is uncovered (as shown in FIG. 7),thereby allowing casting metal to fill the cylinder and the gooseneckready for the next casting operation. The sleeve 50 may be reciprocatedvertically by any suitable means in coordination with opening andclosing movements of the movable die.

In the embodiment of the invention illustrated in FIGS. 7, 8 and 9, thisis accomplished by providing the upper end portion of the sleeve 50 witha rack 51 meshing with a pinion 52 which also engages a horizontallymovable rack 53 connected to the armature 54 of an electromagnet 55.Thus, when the rack 53 moves in one direction to the right as shown inFIG. 7, the sleeve is moved upwardly to align the hole 50a with thefill-port 14a and when it is moved to the left the sleeve is moved tothe position shown in FIG. 9 where the fill-port is closed.

As shown in FIG. 8, the solenoid 55 has two coils 56 and 57 and theseare connected to a reversing switch 58 which in turn is connected to aswitch 59 which is engaged by a lug 60 on the movable die holder 12.When the movable die moves from its wide open position toward the fixeddie, the switch 59 is engaged and this opcrates the reversing switch 58to energize the coil 56 which causes the rack '53 to move to the leftand the sleeve 50 to close the fill-port 14a. This condition remainsuntil the dies have been closed, the plunger 22 operated to inject thecasting metal into the die and to return to suck back the molten metalfrom the nozzle and upper end of the gooseneck and during the time thatthe casting is solidifying. 'It is also maintained until the die carrier12 approaches its wide open position at which time the switch 59 isagain operated, but this time the reversing switch S8 deenergizes thecoil 56 and energizes the coil 57 so that the rack 53 moves to the rightand causes the sleeve 50 to move to its upper position where the hole50a aligns with the fill-port 14a so that the gooseneck may refill.

Instead of the segmental circumferential valve element 22, the shotplunger 22a shown in FIG. 5a may be provided with a radial hole 60 whichintersects a vertical central hole 61 which form a passage for themolten metal from the fill-port 14a to the interior of the cylinder whenthe shot plunger 22a is in the position shown in FIG. 5a. Rotation ofthe shot plunger 22a will move the radial hole 60 away from thefill-port 14a and thus close it off.

The advantage of this construction is that any possible leakage thatmight be present with the segmental valve element shown in FIG. 5a wouldbe prevented by the use of a piston ring which is at the lower end ofthe plunger and always in contact with the wall of the cylinder-15.

It should be understood that the present invention is not limited toeach of the features specifically discussed and illustrated, andalternative embodiments where desired will be obvious to those skilledin the art in the light of the foregoing description. The importantfeatures of the invention comprise an injection plunger capable of rapidmovement between the upper and lower limits of its movement to injectmolten metal into the die cavity and create a vacuum in the injectioncylinder on the reverse stroke, and a valve in operative associationwith the opening and closing of the dies for closing the molten metal inthe injection cylinder to the atmosphere whereby the vacuum ismaintained during solidification of the cast ing and until the dies areseparated.

In this manner, the residual molten metal is drawn down the gooseneckaway from the nozzle and upper section of the 'gooseneck so thatfreezing in these areas is prevented. In fact, aside advantage has beendiscovered in that portions of the sprue of the casting comprising thesprue tip and adjacent areas are also sucked back through the nozzleinto the gooseneck thereby re ducing the amount of metal in the spruewhich must be \rernelted for future re-use.

While portions of the sprue are sucked back into the gooseneck asevidenced by the appearance of the final casting on which the sprue hasa hollow recess where the .tip would ordinarily be, it should beunderstood that none of the molten metal is sucked back from the body ofthe casting. This is so because the cavity formed by the closing of thedies comprises the cavity proper, the sprue opening and narrow runnersand thin gates comunicating there'oetween. Since the dies are relativelycool, the molten metal freezes or solidifies much more rapidly in thegates than it does in either the cavity pro-per or the sprue so that thegates are quickly sealed and prevent the effect of the vacuum fromdisturbing the metal in the die cavity proper.

Variations and modifications may be made within the scope of the claimsand portions of the improvements may be used without others.

I claim:

1. In die-casting apparatus in which molten metal is injected from acylinder through a nozzle and a sprue hole into a cavity formed by fixedand movable die parts when closed to cast articles by operation of aplunger movable between upper and lower limits in a cylinder submergedin a pot of molten casting metal, and receiving molten metal from thepot through a fillport in its wall, the improvement comprising: meansfor causing closing and opening movements to be imparted to the movabledie part; time-controlled means to cause the plunger, after the dies areclosed, to inject molten metal through the gooseneck, nozzle and'spruehole into the, die cavity and subsequently at a predetermined timebefore the openingmovement of the movable die part cause the rapidreturn of the plunger to the upper limit of its movement to withdrawmolten metal from the sprue, nozzle and adjacent part of the gooseneck;and means responsive solely to the closing and opening movements of themovable die part for resep-ectively closing and opening said fill-portwhile the plunger is at the upper limit of its movement.

2. In die-casting apparatus in which molten metal is injected from acylinder through a nozzle and a sprue hole into a cavity formed by fixedand movable die parts when closed to cast articles by operation of aplunger movable between upper and lower limits in a cylinder submergedin a pot of molten casting metal, and receiving molten metal from thepot through a fill-port in its wall, the improvement comprising: meansfor causing closing and opening movements to be imparted to the movabledie part; means to cause the plunger, after the dies are closed, toinject molten metal through the gooseneck, nozzle and sprue hole intothe die cavity and subsequently while the dies remain closed cause thecontinuous return of the plunger to the upper limit of its movement towithdraw molten metal from the sprue, nozzle and adjacent part of thegooseneck; and means responsive solely to the closing and openingmovements of the movable die part for respectively closing and openingsaid fill-port while the plunger is at the upper limit of its movement.I

3. Die-casting apparatus according to claim 2 in which there is a valveelement adapted to open and close the fill-port, and the meansresponsive to the opening and closing movements of the movable die partcauses the valve element to open said'fill-port after the movable die isseparated from the fixed die part.

4. Die-casting apparatus according tonclaim 2 in which the meansresponsive to the closing and opening movements of the movable die partfor closing :andopening the fill-port comprises a valve elementassociated with the fill-port, and mechanical means connecting the valvethe fill-port comprises 8 element with the movable die part forsimultaneous and coordinate movements.

5. Die-casting apparatus according; to claim 4 in which the plunger ismounted for rotation and the valve element comprises a segmental flangedepending from the plunger, and the mechanical means connecting thevalve element to the movable die part comprises a rack andpinion drivewhereby the plunger is rotated to cause the valve flange to close andopen the fill-port as the movable die part is being moved respectivelyto closed and open positions.

6. Die-casting apparatus according to claim 2 in whichthe meansresponsive to the closing and opening movements of the movable die partfor closing and opening the fill-port comprises a valve elementassociated with the fill-port, andin which there are electromagneticmeans for operating the valve element, and switch means connected tosaid electromagnetic means and actuated by said movable die part wherebythe valve is operated to ,close and open the fill-port as the movabledie part is being moved respectively to closed and open positions.

7. Die-casting apparatus according to claim 2 inwhich the meansresponsive to the closing and opening move ments of the movable die partfor closing and opening a sleeve valve fitted between the interiorsurface of the cylinder and the exterior surface of the plunger having afluid passage aligning with the fill-port when the valve is in openposition, and the means responsive to the closing and opening movementsof the movable die part comprises means operated independently or" theoperation of the plunger for reciprocating said sleeve valve axially toalign and disalign the passage therein with the fill-port.

References Cited in the file of this patent. UNITED STATES PATENTS720,714 Lightbrown Feb. 17, 1903 2,004,161 Fausel June 11-, 19352,171,628 Lannert Sept. 5, 1939 2,224,981 Morin Dec. 17, 1940 2,292,266Friden Aug. 4, 1942 2,660,769 Bennett Dec. 1, 1953 FOREIGN PATENTS205,808 Australia J an. 29, 1957

1. IN DIE-CASTING APPARATUS IN WHICH MOLTEN METAL IS INJECTED FROM ACYLINDER THROUGH A NOZZLE AND A SPRUE HOLE INTO A CAVITY FORMED BY FIXEDAND MOVABLE DIE PARTS WHEN CLOSED TO CAST ARTICLES BY OPERATION OF APLUNGER MOVABLE BETWEEN UPPER AND LOWER LIMITS IN A CYLINDER SUBMERGEDIN A POT OF MOLTEN CASTING METAL, AND RECEIVING MOLTEN METAL FROM THEPOT THROUGH A FILL-PORT IN ITS WALL, THE IMPROVEMENT COMPRISING: MEANSFOR CASING CLOSING AND OPENING MOVEMENTS TO BE IMPARTED TO THE MOVABLEDIE PART; MEANS TO CAUSE THE PLUNGER, AFTER THE DIES ARE CLOSED, TOINJECT MOLTEN METAL THROUGH THE GOOSENECK, NOZZLE AND SPRUE HOLE INTOTHE DIE CAVITY AND SUBSEQUENTLY WHILE THE DIES REMAIN CLOSED CAUSE THECONTINUOUS RETURN OF THE PLUNGER TO THE UPPER LIMIT OF ITS MOVEMENT TOWITHDRAW MOLTEN METAL FROM THE SPRUE, NOZZLE AND ADJACENT PART OF THEGOOSENECK; AND MEANS RESPONSIVE SOLELY TO THE CLOSING AND OPENINGMOVEMENTS OF THE MOVABLE DIE PART FOR RESPECTIVELY CLOSING AND OPENINGSAID FILL-PORT WHILE THE PLUNGER IS AT THE UPPER LIMIT OF ITS MOVEMENT.